Control factors in hepatic regeneration will be sought in three areas: 1) Substances, presumably certain key metabolites that are processed by the liver, that arise from the major areas of the body mass and determine the body/liver ratio by informing the liver how much body is present. 2) The modifiers of hepatic regeneration that arise in the portal area (glucagon and other stimulators of hepatic adenyl cyclase plus insulin) and shift DNA synthesis peaks and alter hyperplasia/hypertrophy ratios. As the DNA synthesis peaks are experimentally shifted the relationship of glucagon to hepatic histone phosyhorylation will be determined. 3) Stimulatory or inhibitory substances of hepatic DNA synthesis that arise from the liver itself.